Anionic surfactant, particularly, alkyl sulfate and alkyl polyoxyalkylene sulfate, is excellent in detergency and foaming power, and thus are widely used as cleansing ingredients for domestic or industrial use. An olefin sulfonate, particularly, an internal olefin sulfonate obtained with an internal olefin having a double bond inside an olefin chain, not at its end, as a raw material, has been reported as one of the anionic surfactants.
Such an internal olefin sulfonate is generally obtained by sulfonating an internal olefin through reactions with a gaseous sulfur trioxide-containing gas, followed by neutralization and then hydrolysis of the resulting sulfonic acid. For example, Patent Documents 1 and 2 disclose an improved production method thereof. The internal olefin sulfonate thus obtained is known to have good biodegradability or the like, but is still insufficient in a basic performance as cleansing agent including foamability and foam quality, compared with general-purpose surfactant such as alkyl polyoxyalkylene sulfuric acid ester salt. Thus, further improvement in such basic performance has been desired. As more people have concerned the water-saving or consumers' preferences have been diversified in recent years, the additional value of having excellent foam lubricity in addition to good foamability and volume of foam has also been required for use as major surfactant in laundry detergents, dishwashing detergents, shampoos or the like. Specifically, it has been desired to develop a surfactant composition having excellent foam lubricity which permits smooth spread of foam over the surface of a cleansing target and capable of generating foam in a large amount. Such an additional value is useful for, for example, hair shampoos. There seem to be a growing number of people having their hair damaged by permanent or hair color or having lanky hair without body and stiffness due to aging, regardless of sex. Particularly, when damaged long hair or lanky long hair is washed, the hair tends to be tangled and is thus difficult to wash adequately. Also, one often fails to sufficiently cleanse their hair or scalps because they are concerned about hair breakage or further damage caused by hair washing. If a surfactant composition excellent in foam lubricity and volume of foam can be formulated in a shampoo, the resulting shampoo enables even such long hair to be sufficiently cleansed without causing tangled hair, hair breakage, or further damage.
Then, Patent Document 3 discloses a specific internal olefin sulfonic acid which is intended to impart the solubilizing ability, penetrating ability, and interfacial tension reducing ability as a cleansing component. It discloses that when it is used as, for example, a shampoo, it lathers well without friction, and achieves an improved feel.
Patent Document 4 describes a specific internal olefin sulfonate for the purpose of improving detergency, and discloses examples of application to shampoos, liquid soaps, and the like.
[Patent Document 1] JP-A-01-272564
[Patent Document 2] JP-A-59-222466
[Patent Document 3] JP-A-2003-81935
[Patent Document 4] U.S. Pat. No. 5,078,916